Bobbin signal



8- 1953 R. c. CAMPBELL 2,647,482

BOBBIN SIGNAL Filed D60. 20, 1949 Fig.2.-

Inventor Robert C. Campbell Patented Aug. 4, 1953 BOBBIN SIGNAL RobertC. CampbelLPortsmouth, Va., assignor of one-third to Edward P. Levine,Portsmouth, Va.

Application December 20, 1949, Serial No. 134,100

9 claims, (o1. 112 21s) This invention relates to new and usefulimprovements and structural refinements in signals for sewing machines,and the principal object of the invention is to provide a device of thecharacter herein described, such as may be convene lently andeffectively employed for warning the operator of a sewing machine whenthe supply of thread on the bobbin is nearly exhausted.

This object is achieved by the provision of an electric switch incircuit with a suitable warning device, and means for cperativelyconnecting the switch to the bobbin holder so that as long as the supplyof thread on the bobbin is adequate, the switch remains open and thewarning device inactive, but so that when the thread supply is nearlyexhausted, the bobbin holder is subjected to oscillation or jerking andthe electric switch is accordingly closed, thus energizing the warningmeans.

Some of the advantages of the invention reside in its simplicity ofconstruction, in its emcient and dependable operation, and in itsadaptability for use on sewing machines of different sizes and types. 1

With the above more important objects and features in View, and suchother objects and features as may become apparent as this specificationproceeds, the invention consists essentially of the arrangement andconstruction of parts as illustrated in the accompanying drawings, inwhich:

Figure 1 is an elevational view of a sewing machine .showing theinvention embodied therein.

Figure 2 is an elevational view of a bobbin race having the electricswitch mounted thereon,

Figure 3 is a sectional view of the electric switch and the switchactuating means.

Figure 4 is a perspective view of a slidable keeper and adjusting meansused in the switch, and

Figure 5 is a perspective view of the bobbin such as may be used inconnection with the invention.

Lik characters of reference are employed to designate like parts in thespecification and throughout the several views.

Referring now to the accompanying drawings in detail, the generalreference character designates a conventional sewing machine including,inter alia, a conventional bobbin race l2 containing an oscillatorybobbin holder M which, in turn, accommodates a rotatable bobbin It onwhich is alength of thread IS.

The bobbin holder I4 is also provided with laterally projectin stopfinger 2;] which is adapted for oscillatory movement in a recess 22formed in a stop plate 24, the latter being suitably secured to thebobbin race 12 in the conventional manner.

The invention resides in the provision of an electric switch designatedgenerally by the reference character 25 including a housing 28 providedwith a bracket 38 whereby the entire switch may be secured to the raceI2 or to the stop plate 24, as desired.

A wall 32 of the honing 28 is formed from insulating material and isprovided with a pair of contact points 34, 3 6 which are spaced apartand are electrically connected in series to a suitable warning device,such as for example, an electrical lamp 38 mounted on the machine ID bya bracket 40. The electrical conductor between the lamp and the switchis indicated at 42.

An elongated keeper 44 is slidable in the housing 28 and projectsoutwardly therefrom as indicated at 46, this keeper being provided witha recess or socket 4B accommodating a contact element 50 which isengageable with the contact points 34, 36. The projection portion 46 ofthe keeper 4t accommodates a screw threaded adjusting element 52extending downwardly from the switch and carrying a knurled knob 54,while its upper end portion enters the recess or socket 48 and bearsagainst the underside of a resilient pressure pad 56. This pad, in turn,bears against the contact element 51! and urges the same upwardly inengagement with the contact points 34, 36, it being understood that whenthe element contacts both the points 34', 36 as shown in Figure 3, theswitch is closed, while sliding of the keeper 44 in the direction of thearrow 58 will cause the element 50 to contact only the point 36, inwhich event the switch will be opened. Moreover, by simply tightening orloosening the adjusting element 52, the pressure of the resilient pad 58against the element 50 and, consequently, the pressure of that elementagainst the contact points 34, 36 may be varied, thus correspondinglyvarying the amount of efiort which is required to slide the keeper 4t inthe switch housing 28 to close the switch.

The switch actuating member assumes the form of a rod or stem 60 whichhas one end thereof embedded in the keeper 44 and projects outwardlyfrom the housing 28, the outer end portion of this rod being angulatedas at 62 for engagement with the stop finger 2B of the bobbin holderWhen the invention is placed in use and the supply of thread on thebobbin I B is adequate, the bobbin rotates freely and the bobbin holderI4 is stationary in the race 12, while the stop finger 20 does notcontact the angulated portion 52 of the rod l6 and, consequently, theswitch 26 is in its open position (see Figure 2).

However, when the supply of thread on the bobbin it is exhausted, theinner end of the thread which is usually anchored to the bobbin willcause the bobbin and the entire holder I4 to violently jerk in thedirection of the arrow 64 in Figure 2, under which circumstances thestop finger 20 will engage the rod 60' and will slide the keeper 44 tothe position shown in Figure 3, thus automatically closing the switch 26and energizing the signalling or warning device 38. It will be foundthat by simply tightening or loosening the adjusting means 52, theamount of force required to close the switch may be increased ordecreased accordingly, in proportion to the strength of the particularthread being used, thus safeguarding against undue actuation Of thewarning device and against breakage of the thread.

If it is desired to energize the warning device 38 somewhat in advance,that is, before the supply of thread on the bobbin is actuallyexhausted, the bobbin 16 may be provided adjacent the core 66 thereofwith a transverse pin 68 (see Figure 5) carrying a boss to which issecured a helical spring 72, the first few turns of the thread l8 aroundthe core 66 being wound between the coils of the spring 12 so that theinner end portion of the thread is frictionally held between the coilsof the spring for the purpose of creating the jerking action necessaryfor the actuation of the switch before the supply of thread on thebobbin is actually exhausted.

It is believed that the advantages and use of the invention will beclearly apparent from the foregoing disclosure and accordingly, furtherdescription thereof at this point is deemed unnecessary.

Having described the invention, what is claimed as new is:

1. In a sewing machine including a bobbin race and an oscillatory bobbinholder including a projecting stop finger, an electric switch mountedadjacent said holder and supported directly upon said race, an actuatingmember provided on the switch and positioned behind and disposed in thepath of movement of said finger to be urged by the finger to a circuitclosing position, a bobbin rotatable in said holder, and means on saidbobbin for anchoring an end portion of a thread thereto.

2. In a sewing machine including a bobbin race and an oscillatory bobbinholder including a projecting stop finger, an electric switch mountedadjacent said holder and supported directly upon said race, an actuatingmember provided on the switch and positioned behind and disposed in thepath of movement of said finger to be urged by the finger to a circuitclosing position, and adjustable frictional means for resistingactuation of said switch.

3. In a sewing machine including, a bobbin race and a stop plateprovided with a notch having an extended part, an oscillatory bobbinholder positioned in said race and having a projecting stop fingermovable in said notch, an electric switch mounted directly on saidplate, said switch including spaced contact points, a slidable keeper,and a contact element provided in said keeper and engageable with saidpoints, and a switch actuating member secured to said keeper andextending into the extended part of said notch, said member beingengageable by said finger whereby said switch may be closed.

4. The device as defined in claim 3 together with adjustable meansprovided on said keeper for urging said element in frictional engagementwith said points.

5. For use with the bobbin casing rotating restraining finger of asewing machine, a signal switch comprising a switch casing having aninsulated wall and a slot facing the wall, an insulated keeper slidablyreceived in the casing and having a portion slidably received in theslot, a pair of spaced contacts on said wall facing the keeper, saidkeeper also having a recess facing the Wall, a contact-bridging elementin the recess for engaging and bridging the space between the contactsas the keeper is moved to a circuit closing position, and an actuatorarm secured to the keeper for movement therewith and extending outwardlyfrom the switch casing and disposed in the path of the finger of thebobbin casing.

6. The combination of claim 5 and means threadingly secured to theportion of said keeper and received in the recess for adjusting theelement in the recess to vary the frictional contact of the element withthe contacts.

7. The combination of claim 6 and a resilient pad interposed between theelement and the means threadingly secured to the portion of said keeperfor yieldingly retaining the element in contact with said pair ofcontacts.

8. A signal switch attachment for bobbins, said attachment comprising acasing having an upper insulated wall and a lower wall with a slottherein, a bracket secured to the casing and having fastener receivingopenings, whereby the casing may be secured to a bobbin race, aninsulated operator slidably received in the casing between the upper andlower walls thereof and having a depending sleeve portion received inthe slot for sliding movement, a pair of spaced contacts held on theupper wall and facing the operator, said operator having a recess in itsupper face, a contact element vertically movable in the recess, saidsleeve portion having a threaded bore entering the recess, a resilientplug in the recess under the contact element, an operating rod having anupper portion threaded in the bore and engaging the pad to selectivelyraise and lower the pad and contact element and thereby urge the contactelement and said contacts, and an actuating arm fixed to the operatorand projecting outwardly from the casing to be disposed in the path of abobbin casing restraining finger, whereby the bobbin casing restrainingfinger will engage and urge the operator to a circuit closing positionwith the contact element riding against the contacts.

9. In a sewing machine including a wound bobbin thread which is unwoundduring operation of said machine and a bobbin case having a stop fingerthereon which will be moved beyond its normal thread feeding position asthe thread is unwound a predetermined amount from the bobbin, a switchsupported adjacent said holder and having a sliding circuit making andbreaking ele-' ment, and an actuating arm attached to the element anddisposed in the path of movement of the finger to be engaged by thefinger when the finger is moved beyond its normal thread feedingposition.

ROBERT C. CAMPBELL.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,367,219 Weis Feb. 1, 1921 1,542,808 Adams June 23, 19252,313,638 Granditz Mar. 9, 1943 2,326,852 Haas Aug. 17, 1943 2,350,397Haas June 6, 1944 2,420,275 Winberg May 6, 1947 2,526,279 Roseman Oct.17, 1950

